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Re: 2235 Bad CRT
I you (or anyone else interested) will email me privately, I'll reply
with his phone number. He's internet challenged.... Thanks Peter Florance audserv@... --- In TekScopes@y..., james89es@y... wrote: aBTW he has a lot of old Tek parts to sell (probably dirt cheap as oflot) as his health is not good anymore so he's forced to get out seller?the business. I've bought from him over the years and he's alwaysI may be looking for parts, is there a link or email for this
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Re: 2235 Bad CRT
BTW he has a lot of old Tek parts to sell (probably dirt cheap as aI may be looking for parts, is there a link or email for this seller? Jim |
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Re: 2235 Bad CRT
Miroslav Pokorni
If it is CRT that you are looking for, following web site lists few:
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<> Regards Miroslav Pokorni -----Original Message-----
From: John Miles [mailto:jmiles@...] Sent: Thursday, July 12, 2001 3:46 PM To: 'TekScopes@...' Subject: RE: [TekScopes] Re: 2235 Bad CRT It's a bit of a long shot, but try Tucker Electronics (). They occasionally sell replacement CRTs for Tek and HP instruments. -- jm -----Original Message----- From: audserv@... [SMTP:audserv@...] Sent: Thursday, July 12, 2001 3:19 PM To: TekScopes@... Subject: [TekScopes] Re: 2235 Bad CRT Looking at your auction link then trying the same on this scope with sine wave gave me the answer. the 2 scopes are wounded cousins.... Seller is trying to find a tube. I'd like to keep it as it's really clean but seems than only this one and 2236 used this tube 154-0861- 00. BTW he has a lot of old Tek parts to sell (probably dirt cheap as a lot) as his health is not good anymore so he's forced to get out of the business. I've bought from him over the years and he's always stood behind his sales. Thanks again for all the help and if anyone has tube or junker 2235/2236 I'm interested. Cheers Peter Florance To unsubscribe from this group, send an email to: TekScopes-unsubscribe@... Your use of Yahoo! Groups is subject to |
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Re: 2235 Bad CRT
John Miles
It's a bit of a long shot, but try Tucker Electronics
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(). They occasionally sell replacement CRTs for Tek and HP instruments. -- jm -----Original Message-----
From: audserv@... [SMTP:audserv@...] Sent: Thursday, July 12, 2001 3:19 PM To: TekScopes@... Subject: [TekScopes] Re: 2235 Bad CRT Looking at your auction link then trying the same on this scope with sine wave gave me the answer. the 2 scopes are wounded cousins.... Seller is trying to find a tube. I'd like to keep it as it's really clean but seems than only this one and 2236 used this tube 154-0861- 00. BTW he has a lot of old Tek parts to sell (probably dirt cheap as a lot) as his health is not good anymore so he's forced to get out of the business. I've bought from him over the years and he's always stood behind his sales. Thanks again for all the help and if anyone has tube or junker 2235/2236 I'm interested. Cheers Peter Florance |
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Re: 2235 Bad CRT
Looking at your auction link then trying the same on this scope with
sine wave gave me the answer. the 2 scopes are wounded cousins.... Seller is trying to find a tube. I'd like to keep it as it's really clean but seems than only this one and 2236 used this tube 154-0861- 00. BTW he has a lot of old Tek parts to sell (probably dirt cheap as a lot) as his health is not good anymore so he's forced to get out of the business. I've bought from him over the years and he's always stood behind his sales. Thanks again for all the help and if anyone has tube or junker 2235/2236 I'm interested. Cheers Peter Florance --- In TekScopes@y..., "John Miles" <jmiles@p...> wrote: The key point is that damage to the mu-metal shield will NOT cause ashield's ability to keep external fields out. If your visual glitch doesn'tchange shape with the horizontal timebase, it can't be caused by anexternal AC field (e.g., 60 Hz from the power transformer). It can only becaused by a DC magnetic source, of which there aren't any in an oscilloscope,or by a deformed deflection structure internal to the CRT.rattling around inside the tube scraping the coating off the screen. If youturn the scope upside down and shake it, it'll probably look like someonewent crazy with an Etch-A-Sketch.were you I'd be looking for at least a partial rebate on the sales price onthis one.
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Re: 2235 Bad CRT
Ashton Brown
John Miles wrote:
Ah.. RTP indeed. Apologies for red herring. In rush reading, and remembering the wrong detail - indeed such a localized 'spot' unchanged by timebase setting Isn't bloody likely to be other than a malformed or otherwise screwy internal piece. Or a bizarre local effect more ikely to be found in a superconducting lab :[ As EmilY Litella said, "never mind!" :-) (I miss Gilda Radner) Ashton |
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Re: 2235 Bad CRT
John Miles
The key point is that damage to the mu-metal shield will NOT cause a
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magnetic anomaly to appear on the screen -- it will only impair the shield's ability to keep external fields out. If your visual glitch doesn't change shape with the horizontal timebase, it can't be caused by an external AC field (e.g., 60 Hz from the power transformer). It can only be caused by a DC magnetic source, of which there aren't any in an oscilloscope, or by a deformed deflection structure internal to the CRT. The black spots in your CRT phosphor are caused by solid objects rattling around inside the tube scraping the coating off the screen. If you turn the scope upside down and shake it, it'll probably look like someone went crazy with an Etch-A-Sketch. Your CRT is damaged; it's not the shield or anything else. If I were you I'd be looking for at least a partial rebate on the sales price on this one. -- jm ----- Original Message -----
From: "Ashton Brown" <ashtonb@...> To: <TekScopes@...> Sent: Thursday, July 12, 2001 12:53 PM Subject: Re: [TekScopes] 2235 Bad CRT I'm not at all sure how many ergs you have to transmit locally; I recallbreak a waslot of other components, too. Having a magnet do that is more plausible. doannealed at possibly -recall: these runninga new aCRT out of upwards.strange problem. middle,When at the bottom Ithe line is could find.
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Re: 2235 Bad CRT
Ashton Brown
I'm not at all sure how many ergs you have to transmit locally; I recall
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that we deemed the smaller ones - used around photomultiplier tubes - to be "rather fragile" = not to be dropped on floor even.. Agreed re "whole scope" ~number of G's likely to transmit that much force to the shield, qithout probably cracking boards etc. (But I've seen some dropped scopes, visibly mangled - still work! Tek heap good G-tester folk.) Now something falling on shield, with scope open? And especially a local hit - like a rod, say? Needn't necessarily produce a visible mark in the paint. So.. not enough info for more than a guesstimate. Still - if you hunt up a CRT and that wasn't it? Just a thought. Ashton Miroslav Pokorni wrote:
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Re: 2235 Bad CRT
Miroslav Pokorni
I do not claim to know it as a fact, but it seems to me that a blow that
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would upset crystal lattice of Mu metal, i.e. wreck annealing, would break a lot of other components, too. Having a magnet do that is more plausible. Regards Miroslav Pokorni -----Original Message-----
From: Ashton Brown [mailto:ashtonb@...] Sent: Wednesday, July 11, 2001 7:05 PM To: TekScopes@... Subject: Re: [TekScopes] 2235 Bad CRT Hmmm - dropped you say? Mu metal shield around CRT. It was annealed at birth. Dunno chracteristics of Tek's exact choices but do recall: these shields cannot stand a large blow to metal. Just possibly - a new shield would be enough, from a parts-hog. Or try running CRT out of shield (yes a PITA to set up). As to reannealing - have long since forgotten temp you might have to get it up to and.. the drill for cooling - all rather critical IIRC) Good luck! Ashton John Miles wrote: > > It was probably dropped. I assume a sine-wave display looks like the 485 I > sold on ebay awhile back: ... if so, > that's the problem. Nothing you can do about it, unfortunately. > > -- jm > > -----Original Message----- > From: Peter Florance [SMTP:audserv@...] > Sent: Wednesday, July 11, 2001 11:55 AM > To: 'TekScopes@...' > Subject: [TekScopes] 2235 Bad CRT > > Hello > New to the list > Purchased a TEK 2235M with low hours on it and it has a strange problem. > With input grounded, moving trace up and down, either trace distorts. When > trace is at the top, the left 1/2" is distorted upwards. When at the bottom > > there is a 1/2" area near the right side of the CRT is distorted downwards. > > Like the CRT is magnetized or something. Near the middle, the line is > pretty straight. Looking at verticle deflection plates with another scope I > > don't see any AC signal at all. Like it's coming from inside the tube. > Trace is bright and sharp other than bends in it > Bad CRT? > Nothing magnetic stuck to shield or anywhere else that I could find. > > Thanks for your help! > > Peter Florance > audserv@... > > To unsubscribe from this group, send an email to: > TekScopes-unsubscribe@... > > > > Your use of Yahoo! Groups is subject to To unsubscribe from this group, send an email to: TekScopes-unsubscribe@... Your use of Yahoo! Groups is subject to |
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Re: Sources for Terminations
Miroslav Pokorni
I am sorry to say, but military does not have a corner on being cheap, you
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should see purchasing agents in commercial companies, especially those with 'empire building' mindset. It must be at these 'purchasing workshops' that they get told the first object of game is to avoid buying a brand name product. They would spend couple of hours to come up with some off brand (probably 'purchasing agent network' exchanges information on low bidders) and then you have to spend another few hours re-evaluating product that you already specified, all that to save few bucks or find out that product does not meet requirements, but those details never stand in the way of purchasing agent claims of how much money they saved to company. By the way, regarding this $500 hammer. When military was dredged over coals for buying $3500 coffee makers, Delta Airlines bought this same coffee makers for $4500 a piece; it is that Delta bought 3 pieces, and military ordered 5, so military got a price brake. Those were not your Mr. Coffee machines, these were flight-worthy devices. Regards Miroslav Pokorni -----Original Message-----
From: dhuster@... [mailto:dhuster@...] Sent: Thursday, July 12, 2001 6:57 AM To: TekScopes@... Subject: [TekScopes] Re: Sources for Terminations When I was in the Navy in the mid-1970's, we would order the 011-0049- 00 using the FSN. Amazing what the military can do to you when they decide to get something cheaper. We didn't get Tek terminations. Instead, we got these low-bidder things that were all chromed (or nickel, or whatever), few of them measured exactly 50 ohms and most of them fell apart in our hands with the first use! I think we'd rather have had a $500 hammer! And if you wanted the REAL thing from Tek, you had to order them "open purchase" (or direct from a commercial vendor vs. throught the normal military supply system) which was always a real hassle in justification, etc. And even then, if your ordered something like that "open purchase", often our own supply folks would do us the "favor" of discovering that the part we wanted had an FSN and we'd end up with the inferior parts anyway! Dean To unsubscribe from this group, send an email to: TekScopes-unsubscribe@... Your use of Yahoo! Groups is subject to |
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Re: Sources for Terminations
When I was in the Navy in the mid-1970's, we would order the 011-0049-
00 using the FSN. Amazing what the military can do to you when they decide to get something cheaper. We didn't get Tek terminations. Instead, we got these low-bidder things that were all chromed (or nickel, or whatever), few of them measured exactly 50 ohms and most of them fell apart in our hands with the first use! I think we'd rather have had a $500 hammer! And if you wanted the REAL thing from Tek, you had to order them "open purchase" (or direct from a commercial vendor vs. throught the normal military supply system) which was always a real hassle in justification, etc. And even then, if your ordered something like that "open purchase", often our own supply folks would do us the "favor" of discovering that the part we wanted had an FSN and we'd end up with the inferior parts anyway! Dean |
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Re: 2235 Bad CRT
Thanks for the replies.
Other than that, scope is in perfect cosmetic condition. Guessing switches should be a little noisy from dis-use, but don't appear to be. Shield on this unit is pretty simple looking - just a dunce cap with cut-outs for deflection plat pins. I have some mu metal but am no tin- banger. BTW, there are one or two black specs on the INSIDE of the glass. Paid 400.00 locally for the scope which was with probes book and cords. Worth trying locate used tube? Thanks again Peter --- In TekScopes@y..., Ashton Brown <ashtonb@j...> wrote: Hmmm - dropped you say? Mu metal shield around CRT. It wasannealed at birth. Dunno chracteristics of Tek's exact choices but do recall:these shields cannot stand a large blow to metal. Just possibly - a newthe 485 I if so,sold on ebay awhile back: ... problem.that's the problem. Nothing you can do about it, unfortunately. distorts. WhenWith input grounded, moving trace up and down, either trace the bottomtrace is at the top, the left 1/2" is distorted upwards. When at downwards. line is another scope Ipretty straight. Looking at verticle deflection plates with tube. find.Trace is bright and sharp other than bends in it
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Re: 2235 Bad CRT
Ashton Brown
Hmmm - dropped you say? Mu metal shield around CRT. It was annealed at
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birth. Dunno chracteristics of Tek's exact choices but do recall: these shields cannot stand a large blow to metal. Just possibly - a new shield would be enough, from a parts-hog. Or try running CRT out of shield (yes a PITA to set up). As to reannealing - have long since forgotten temp you might have to get it up to and.. the drill for cooling - all rather critical IIRC) Good luck! Ashton John Miles wrote:
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Re: 2235 Bad CRT
John Miles
It was probably dropped. I assume a sine-wave display looks like the 485 I
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sold on ebay awhile back: ... if so, that's the problem. Nothing you can do about it, unfortunately. -- jm -----Original Message-----
From: Peter Florance [SMTP:audserv@...] Sent: Wednesday, July 11, 2001 11:55 AM To: 'TekScopes@...' Subject: [TekScopes] 2235 Bad CRT Hello New to the list Purchased a TEK 2235M with low hours on it and it has a strange problem. With input grounded, moving trace up and down, either trace distorts. When trace is at the top, the left 1/2" is distorted upwards. When at the bottom there is a 1/2" area near the right side of the CRT is distorted downwards. Like the CRT is magnetized or something. Near the middle, the line is pretty straight. Looking at verticle deflection plates with another scope I don't see any AC signal at all. Like it's coming from inside the tube. Trace is bright and sharp other than bends in it Bad CRT? Nothing magnetic stuck to shield or anywhere else that I could find. Thanks for your help! Peter Florance audserv@... |
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2235 Bad CRT
Hello
New to the list Purchased a TEK 2235M with low hours on it and it has a strange problem. With input grounded, moving trace up and down, either trace distorts. When trace is at the top, the left 1/2" is distorted upwards. When at the bottom there is a 1/2" area near the right side of the CRT is distorted downwards. Like the CRT is magnetized or something. Near the middle, the line is pretty straight. Looking at verticle deflection plates with another scope I don't see any AC signal at all. Like it's coming from inside the tube. Trace is bright and sharp other than bends in it Bad CRT? Nothing magnetic stuck to shield or anywhere else that I could find. Thanks for your help! Peter Florance audserv@... |
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Re: Coax BNC Cable Termination
Miroslav Pokorni
The midnight oil that would have been spared if you used sinewave would have
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been spent on debugging problem coming from jitter of sinewave clock, so I do not think that you have anything to regret. As for coax cable, unless you used a ? inch rope (RG6) or foamed dielectric (what was very expensive 10 years ago), your standard ? inch cable would have been around 30 pF/ft, 5 pF give or take, so you were dealing with 450 pF load. A driver that comes to mind is National's DS0026, which is characterized for 500 and 1000 pF load (I had to actually go and check for what loads is driver characterized), but that is a driver that was not widely known or used, so its availability might have been poor. Regards Miroslav Pokorni -----Original Message-----
From: F F [mailto:ferfons@...] Sent: Wednesday, July 11, 2001 1:42 AM To: TekScopes@... Subject: Re: [TekScopes] Coax BNC Cable Termination Re John's comments, I agree and I'm pretty sure a sinewave would had spared me the midnight oil ;-) Re Miroslav comments, I can't remember the cable's cap spec - this took place some ten odd years). What I can tell you though is in fact it wasn't easy to pick a suitable driver for this application. Fernando Portsmouth, UK >From: "John Miles" <jmiles@...> (snip...) Also keep in mind that a 1 MHz square wave needs at least 10 MHz of error-free bandwidth, preferably more, to come out looking right. With a sine wave, you might never have noticed the problem. >From: Miroslav Pokorni <mpokorni@...> (snip...) >The 5 meters of cable is still 450 pF, still quite load for most drivers. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at . To unsubscribe from this group, send an email to: TekScopes-unsubscribe@... Your use of Yahoo! Groups is subject to |
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Re: Coax BNC Cable Termination
F F
Re John's comments, I agree and I'm pretty sure a sinewave would had spared me the midnight oil ;-)
Re Miroslav comments, I can't remember the cable's cap spec - this took place some ten odd years). What I can tell you though is in fact it wasn't easy to pick a suitable driver for this application. Fernando Portsmouth, UK From: "John Miles" <jmiles@...>(snip...) Also keep in mind that a 1 MHz square wave needs at least 10 MHz of error-free bandwidth, preferably more, to come out looking right. With a sine wave, you might never have noticed the problem. From: Miroslav Pokorni <mpokorni@...>(snip...) The 5 meters of cable is still 450 pF, still quite load for most drivers._________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at . |
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